1. Technological Field
The present disclosure relates generally to antenna apparatus and systems for use in wireless devices, and more particularly in one exemplary aspect to a multi-tap frequency switchable antenna apparatus, and methods of operating and using the same.
2. Description of Related Technology
Various configurations of frequency switchable antenna apparatus are known in the related arts. For example, co-owned U.S. Pat. No. 8,564,485 to Milosavljevic et al. discloses an adjustable multi-band antenna for use in mobile terminals and radio devices. The adjustable multi-band antenna includes an adjusting circuit for the antenna that is galvanically connected to a point on a radiator. The adjusting circuit can affect the operation of the antenna in two operating bands and includes a multi-pole switch, by which the radiator point can be connected to one of alternative transmission lines. For example, one of two transmission lines is open and another shorted. A discrete capacitor can be located between the separate conductor of the transmission line and an output pole of the switch as an additive-tuning element. The adjusting circuit further includes an LC circuit disposed between the radiator and the switch. The lengths of the transmission lines, the values of the discrete components and the distance between the antenna short-circuit point and the adjusting circuit connecting point are then variables for the purposes of adjusting the operating band for the antenna. Various values are calculated for these variables such that the antenna operational bands are able to shift to a desired frequency when the switch state is changed.
As yet another example, co-owned U.S. Pat. No. 8,618,990 to Somero discloses a wideband antenna for use in portable radio devices. For example, a monopole antenna is used within a laptop computing device. The antenna includes a monopole radiator coupled to an auxiliary ground plane element and is placed outside of the footprint of the computer display ground plane. The auxiliary ground element is configured not to have electrical connections to the ground plane of the laptop computer. Alternatively, a solid state switch selectively connects an antenna parasitic element to the main ground thus enabling selective control of the antenna lower frequency operating band.
For each of the foregoing variety of antenna configurations, although the desired frequency bands for the antennas are switchable, the overall operational bands for these antennas are relatively narrow and the number of available operational bands is limited. Moreover, due to the overall volume constraints available within widely available extant mobile terminals and wireless devices, the electrical dimensions available for these switchable antennas are limited. Hence, there is a salient need for an improved antenna system that is constructed so as to improve upon the flexibility in operational band usage over prior art devices, while simultaneously occupying a limited volume within existing mobile terminals and wireless devices.